1. Field of the Invention
The present invention relates to a method of manufacturing SOI substrates having a so-called silicon-on-insulator (SOI) structure as which a semiconductor layer is provided on an insulating surface and a method of manufacturing semiconductor devices having an SOI structure.
2. Description of the Related Art
As an alternative to an integrated circuit using a silicon wafer which is manufactured by thinly slicing an ingot of a single-crystal semiconductor, an integrated circuit using a semiconductor substrate which is referred to as a silicon-on-insulator (hereinafter also referred to as “SOI”) substrate, as which a thin single-crystal semiconductor layer is provided on an insulating surface has been developed. The integrated circuit using an SOI substrate has attracted attention as an integrated circuit in which parasitic capacitance between a drain of a transistor and the substrate is reduced and the performance of a semiconductor integrated circuit is improved.
As a method of manufacturing SOI substrates, a hydrogen ion implantation separation method is known (e.g., see Reference 1: Japanese Published Patent Application No. 2000-124092). The hydrogen ion implantation separation method is a method in which hydrogen ions are implanted into a silicon wafer to form an embrittlement layer at a given depth from the surface, and a thin silicon layer is bonded to another silicon wafer by separation of the silicon wafer from the embrittlement layer as a separation plane. In addition to the heat treatment for separation of a silicon layer, it is necessary to perform heat treatment in an oxidizing atmosphere to form an oxide film over the silicon layer, remove the oxide film, and perform heat treatment at 1000° C. to 1300° C. to increase bonding strength.
Furthermore, a semiconductor device in which an insulating substrate such as high heat resistance glass is provided with a silicon layer is disclosed (e.g., see Reference 2: Japanese Published Patent Application No. H11-163363). This semiconductor device has a structure in which the entire surface of crystallized glass having a distortion point of 750° C. or more is protected by an insulating silicon film and a silicon layer obtained by a hydrogen ion implantation separation method is adhered to the insulating silicon film.